On Monday, FBI agents raided the headquarters of Pilot Flying J in Knoxville.

Haslam reiterated to the media that the company is cooperating 100-percent with investigators. He said they were "Shocked by the events of yesterday."

Haslam did confirm that the criminal investigation centers on the application of customer rebates. Haslam said a very small number of customers claim they were not paid rebates they were owed. "We disagree with that," said Haslam.

Beyond that, Haslam said he knew very little about the particulars of the investigation.

Bill Killian, the U.S. Attorney in Knoxville, told The Associated Press that four search warrants have been served on Pilot. He said the reasons for the warrants are sealed.

FBI and Internal Revenue Service agents locked down the Pilot Flying J headquarters Monday and ordered employees out of the building as they conducted their search.

When asked what he would say to Browns fans, Haslam said he wanted to apologize to the City of Cleveland and the Browns fans. "The last thing we wanted to do is put a potential blemish on the city we've come to love, even though, we believe we did nothing wrong."

Haslam says he will be in Cleveland later this week and next week as the team prepares for the NFL Draft.

Jimmy Haslam stepped down as company CEO after buying the Browns last summer. He returned as CEO in February, replacing former PepsiCo President John Compton.

Tennessee Governor Bill Haslam has no position with the company but still has an unspecified holding in it, according to his limited financial disclosures.

Pilot Flying J retail operations remain open. Jimmy Haslam sent letters to workers encouraging them to focus on their work.